Why is this Mesh broken up?
Sometimes Importers will separate things into multiple meshes, or even multiple separate objects. It looks like the mesh in the picture is still one object, but the mesh has been "cut" along various seams. First thing to try, in Edit mode, select the entire mesh, open the space-bar search, and and find the "Remove Doubles" tool. You may have to adjust the merge distance option, depending on the size of your mesh.